This invention relates generally to a feel bumper for providing feedback to an operator when an input device is moved to a predetermined initial operating position and then past the initial position through a range of subsequent positions, and more particularly, to a feel bumper which provides a distinctive high feedback force or load when the input device is moved to the initial operating position and lower feedback forces when moved through the range of subsequent positions.
Input devices, such as, but not limited to, lever operated single and dual axis pilot control valves, are often provided with some type of associated feedback device, such as a feel bumper or the like, for signaling to the operator when the input device is moved to an initial predetermined position for performing certain operating functions, such as, but not limited to, commonly known xe2x80x9cquick dropxe2x80x9d, xe2x80x9cfloatxe2x80x9d or xe2x80x9cfloat downxe2x80x9d functions in the instance of input devices of work machines such as those with a blade or bucket. Some known input devices also use a magnetic detent including an electromagnet to hold the pilot valve spring and pressure generated centering loads as well as loads generated by the feel bumper and G-load forces.
One problem associated with some of the known feel bumpers is that they utilize a low initial feedback force, or preload, so as to be only marginally effective in keeping the input device from inadvertently being moved to or past the predetermined initial position. In other known devices, the feel bumpers are set with an acceptable preload, but then the magnetic detent hold force is low. In still other known devices, the magnetic detent hold force is higher, but this is disadvantageous as it requires a coil which must be larger for generating the magnetic force and requires higher amperage.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
According to one aspect of the present invention, a feel bumper is disclosed including a plunger disposed for movement by an input device along a predetermined path, and at least one damper element disposed to engage the plunger when in a predetermined initial position along the path corresponding to a desired operating position for exerting a first opposing feedback force against the plunger in opposition to movement thereof along the path in a first direction, the at least one damper element being yieldable to the plunger when moved in the first direction past the predetermined initial position and exerting a second opposing feedback force against the plunger in opposition to the continued movement of the plunger in the first direction, the second opposing feedback force being less than the first opposing feedback force.
According to a preferred aspect of the invention, the damper element includes at least one ball disposed to be urged by the plunger against a shoulder located along the path of movement when the plunger is at the predetermined initial position for generating the first opposing feedback force, the at least one ball being displaceable past the shoulder by movement of the plunger in the first direction with a sufficient force to overcome the first opposing feedback force and allow the input device to move to the subsequent operating positions.
According to another aspect of the invention, a resilient biasing member can be disposed to oppose the movement of the plunger in the first direction along a predetermined portion of the path, the resilient biasing member generating at least a portion of the second opposing feedback force.
According to another preferred aspect of the invention, the at least one damper element can include a generally C-shape element for generating the first opposing feedback force which is resiliently compressible for yielding to the continued movement of the plunger in the first direction past the predetermined initial position for allowing the input device to move to the subsequent operating positions.
According to another aspect of the present invention, a feel bumper is disclosed having a housing including a first internal side wall portion defining a first cavity portion, a second internal side wall portion defining a second cavity portion, and an internal shoulder forming an opening connecting the first cavity portion and the second cavity portion. The feel bumper further includes a plunger disposed in the first cavity portion for movement toward the opening, and at least one damper element positioned in the first cavity portion between the plunger and the shoulder, the at least one damper element being displaceable or compressible so as to be forced into the opening due to contact with the shoulder and the plunger when moved toward the opening to a predetermined position so as to generate a first opposing feedback force in opposition to the movement.